The invention relates to an electrolyzer suitable for the production of chlorine and caustic alkalies from an aqueous alkaline chloride solution. The electrolyzer normally consists of a plurality of electrolyzer elements assembled in the manner of a filter-press.
Electrodes, i.e., anodes and cathodes, must be in as close a contact as possible with an intermediate membrane or diaphragm, but arranged in such a manner that the membrane or diaphragm is not damaged due to excessive contact pressure, thus causing metallic contact between the anode and cathode.
German Pat. No. DE-PS-12 52 643 describes an electrolyzer including a diaphragm or membrane which is arranged between an anode and a cathode, such diaphragm consisting of a non-conductive porous asbestos and the membrane being made of an ion exchanger resin. According to the patent, the anode and cathode are placed directly on the diaphragm. The elements are permeable such that the products can be withdrawn from the electrolyzer. The cathode, which has an asbestos fiber layer constituting a diaphragm, is pressed against the anode by means of a flexible support of the electrodes. This method, however, does not ensure a uniform surface contact of anode and diaphragm.
German Pat. No. DE-OS 30 28 970 describes a design in which an anode and a cathode are in a direct multi-point contact with the membrane via a conductive flexible layer. For this purpose, a flexible current collector is used and combined with a rigid support plate. The current collector is a mesh of 0.15 mm. nickel wire. Since there is only a linear or multi-point contact of the two adjacent cathode elements, the contact surface is relatively small in relation to the overall cathode surface. This configuration causes a substantial voltage drop.